I've had problems from time to time with mites on some of my boys... not in the usual places. Check over his entire body. Also, consider the weather. These are a Mediterranean breed and though I know California is quite warm, it isn't warm enough in March/April, not enough warm light hours! I have the same issues when its early in the year. They definitely like the warmth. So, if its not mites and they're not sick, give them a little more time. And more time out in the sun if you can.